Motion cues increase focused attention towards purely visual stimuli in a nocturnal primate and drive stimulus...

Visual information is of pivotal ecological importance to monkeys, apes, and humans, whereas its role in nocturnal primate ecology is less well understood. We explored how purely visual information modulates the behavior of a nocturnal primate. Abstract (shape), photographic (shape + detail), or video (shape + detail + motion) representations of arthropod prey (Zophobas morio; food context) or a male conspecific (social context) were systematically presented to 22 individuals of the gray mouse lemur (Microcebus murinus) using a touchscreen. We assessed stimulus-directed touch interactions, durations of focused visual attention towards the different stimuli, and durations spent in the half of the setup-chamber more distant to the touchscreen (as quantification of approach/avoidance). Focused attention towards the stimulus generally increased from abstract and photographic to videographic stimuli. For the food context, indications for a parallel increase in stimulus-directed touch interactions from abstract stimulus to video were found. Approach/avoidance was independent of the stimulus type within both contexts. A comparison between the contexts under the video condition revealed higher durations of visual attention and lower stimulus avoidance in the food context compared to the social context. The number of touch interactions with the video stimulus was not generally context-dependent, but context-dependency related to sex: In the food context, animals with high and low numbers of touch interactions were equally distributed across sexes. In the social context, females showed the highest numbers of touch interactions. Numbers in males declined compared to the food context. Our results demonstrate for the first time that purely visual information modulates mouse lemur behavior and focused attention in a content- and context-specific manner, suggesting that vision is of high importance for the ecology of these nocturnal primates. The findings emphasize the need for further vision-based experiments to gain deeper insight into the evolution of visual information processing and cognition in nocturnal primates.